Wood chipper

ABSTRACT

Wood chipper having a rotary disc with spirally mounted L-shaped wing knives to effectively sequentially slice the surface of the wood stock into a plurality of elongated segments which are automatically broken into chips, each segment being produced by cutting the wood surface simultaneously in multiple directions and at a predetermined depth. Thus, initial orientation of the bulk waste is unnecessary.

I v Un ted States .1 Patent [-151 3,661,331 Ballew [4 1 May 9, 1972 [54] WOOD CHIPPER 2,655,319 10/1953 Johnson ..241/92 525,195 8/1894 Egner ..24l/92 [72] inventor. Earl Ballew, Route 2, PO. Box 160, Blue 1,436,208 11/1922 Sprague 44,176 UX 30513 2,183,224 12/1939 Norman ..241/92 [22] Filed: Sept. 8, 1969 Primary Examiner-Donald G. Kelly [2 App Nod 856,063 Attorney-Jacobi, Lilling & Siegel 52 us. c1 ..241/92 [57] ABSTRACT [51] Int. Cl... "B021: 18/06 Wood chipper having a rotary disc with spirally mounted L- [58] Field of Search ..241/92, 278, 56, 296-298; Y shaped wing knives to effectively sequentially slice the surface 144/17 of the wood stock into a plurality of elongated segments which are automatically broken into chips, each segment being [56] References Cited produced by cutting the wood surface simultaneously in multiple directions and at a predetermined depth. Thus, initial U T D T T P T orientation of the bulk waste is unnecessary. 1,039,441 9/l 912 Ray ..24 1/92 7 Claims, 5 Drawing Figures P'A'TENTEDMAY' 9 1912 SHEET 1 OF 2 FIG. 5

FIG. E

IN V EN TOR E RL BALLEW m A T TORNE Y5 PATENT'ED MAY 9 I972 SHEET 2 BF 2 IN V LN 1 0R. EARL BALLEW A TTORNEYS W001) CI-IIPPER BACKGROUND OF THE INVENTION This invention generally relates to wood chippers and particularly concerns an improved apparatus for producing wood chips from wood stock.

The primary market for wood chips perhaps can be found in the paper and pressed board industries which annually consume enormous quantities of wood chips in the production of paper goods by chemical digestion processes, and the like. For reasons of conservation and economy, waste wood rather than round wood isutilized as the raw material or stock from which wood chips are produced. Waste wood, such as, logs, sawmill waste, trim blocks, and other scraps, is of irregular size and fiber orientation and herein arises a significant technical problem as the wood chips produced therefrom must have substantially uniform characteristics, such uniformity being required by the paper and allied industries to ensure quality processing.

When utilizing prior art wood chipping apparatus and techniques, the production of wood chips having uniform characteristics is quite difiicult even under the best of conditions. In any event, the production of uniform wood chips directly from irregular waste approaches a near impossibility in the prior art. This is the case since the typical prior art wood chipping apparatus utilizes a cutting technique and mode of operation wherein a surface of a piece of wood stock is generally sliced through in one stroke in a single direction along a single cutting plane. If the fibers of the wood stock are disposed transverse or crosswise to the single cutting plane, a possibility of producing fairly uniform wood chips results as a cross-grain cut would be achieved, although inherent dimensional inconsistency is still prevalent since the entire wood surface is sliced at once. However, if the fiber of the wood stock is disposed generally parallel to the single cutting plane, only useless splintering and slivers result as the cut would be with the grain rather than crosswise.

Accordingly, the typical prior art apparatus require that the wood stock or at least the fibers thereof fed into the wood chipper be oriented in a predetermined position. This orientation requirement effectively precludes the utilization of waste wood having physical dimensions below certain given minimums and necessitates a preliminaryselection operation upon the bulk waste so as to eliminate the stock therein having unsuitable dimensions. This waste could be run through prior artmachines but with extremely poor chip recovery. This rejected stock then is disposed of such as by burning, hauling, or

the like. Of course, the inability of the prior art to utilize all sizes of waste wood and operate directly upon bulk waste comprises an inherent inefficiency which raises the cost of wood chips to the industry, increases mill operating costs, and ultimately increases their product cost to the consumer.

SUMMARY OF THE INVENTION Thus, a need exists in the art for a wood chipping apparatus which effectively eliminates the aforementioned disadvantages of the prior art. It is a primary object of the instant invention to provide a novel apparatus which fills this need. Further, more specific, yet equally important objects of the instant invention are:

The provision of a novel apparatus for producing wood chips having substantially unifonn size from bulk wood waste, including trim blocks and stock of small dimensions;

The provision of a novel apparatus which produces optimum wood chips at a cost far below that heretofore attainable in the prior art;

The provision of a novel apparatus which produces wood chips which consistently are of specified, uniform dimensions;

The provision of a novel apparatus which, from a conservation standpoint, produces a superior chip yield in that a negligible amount of waste or scrap is generated as compared with prior art apparatus;

The provision of a novel apparatus for producing wood chips which require no preselection of wood stock nor require any orientation thereof;

The provision of a novel wood chipping apparatus of relatively simple, yet efficient, construction;

The provision of a novel wood chipping apparatus which requires relatively low operational power; and,

The provision of a novel wood chipping apparatus which affords safe and reliable operation.

The objects as well as others which will become apparent as the description proceeds, are implemented by the instant invention which comprises an apparatus for wood chipping and constitutes a new approach in the art. Use of the novel apparatus for producing wood chips directly from bulk wood stock includes the steps of initially cutting a surface of the wood stock simultaneously in multiple directions at a predetermined depth along an arcuate path of travel. in this fashion, at least one elongated segment of wood is removed from the surface of the stock, this segment generally being of regular dimension due to the controlled depth and multidirectional nature of the cut which assures cross-grain severing of the segment regardless of fiber orientation. Accordingly, and in contrast to the prior art, initial orientation of the wood stock is not necessary.

The segment so removed from the surface of the wood stock is broken into chips of uniform length and the process is cyclically repeated until the wood stock is consumed. Preferably, only a portion of the wood stock surface is initially cut and removed as an elongated, arcuate segment, and, thereafter, adjacent portions of the wood surface are sequentially cut to the same predetermined depth, whereby a plurality of wood segments are formed from a single surface of the wood stock. After the surface has been cut and transformed into segments of the same depth, an underlying surface area would be acted upon in the same manner, again until the wood stock itself was consumed. Of course, each of the segments of wood so produced would individually be broken into wood chips having substantially uniform dimensions.

The novel wood chipping apparatus for carrying out the techniques above discussed, preferably comprises a rotating disc or planar circular plate of heavy steel with a plurality of knives secured in and protruding a common distance from a planar surface thereof. In the preferred inventive embodiment, each of the knives comprises an L-shaped wing knife which preferably defines first and second orthogonal cutting edges. The knives are disposed in the surface of the plate such that the first cutting edge of each knife generally extends parallel to the planar plate surface in a single common plane and such that the adjoining second edge of each knife extends generally transverse to and towards the planar plate surface. The knives are contemplated to be disposed about the plate surface at different radial distances from the rotational axis thereof such that the knives preferably are disposed in a spiral curve with the. difi'erence in radial distances of disposition between adjacent knives in the spiral curve being such that the first cutting edges of the knives sweep through overlapping cutting paths during rotation of the plate.

The wood stock is fed towards the rotating disc or plate, transverse to the rotational plane thereof. Each knife on the plate sequentially slices a segment from the surface of the wood stock by actually cutting the surface of the wood stock simultaneously in multiple directions and at the predetermined depth detennined by the amount of protrusion of the knife from the plate surface. During each rotation of the plate, a plurality of segments are cut and thus a layer of wood of predetermined thickness is removed from the surface of the wood stock. In effect, then, the knives can be thought of as undergoing a lateral stepwise oscillation across the entire surface of the plate. The segments of wood so produced pass through knife slots or throughbores in the rotating plate whereat the segments are broken into predetermined lengths and formed into substantially uniform chips, the chips then being deposited into a hopper.

Since each knife in the preferred inventive embodiment has two transverse cutting edges, cross-grain severing of the wood stock is ensured regardless of initial orientation. The dimensioning of the first and second cutting edges of each knife fixes the breadth and width of each segment of wood cut from the wood stock surface and, since the segments are broken at regular intervals along the length thereof, the wood chips produced by the novel machine are of a selected substantially uniform dimension.

BRIEF DESCRIPTION OF THE DRAWINGS The invention itself will be better understood and further advantageous features thereof will become apparent from the following detailed description of a preferred inventive embodiment, such description referring to the appended sheets of drawings, wherein:

FIG. 1 is a perspective view, partially broken away, for clarity, of the general over-all arrangement of the wood chipper apparatus of the instance invention;

FIG. 2 is an enlarged section of the novel apparatus taken along the line 22 of FIG. 1, diagrammatically delineating the mode of operation;

FIG. 3 is a fragmentary plan view of the planar face surface of the rotary cutting disc of the novel invention, illustrating the dispostion of cutting knives thereon;

FIG. 4 is a plan view of the planar rear surface of the rotary cutting disc of the instant invention; and,

FIG. 5 is an exploded, perspective view of an individual knife as utilized with the instant invention, and the holding means therefor.

DETAILED DESCRIPTION OF A PREFERRED INVENTIVE EMBODIMENT Now, reference is to be had to the drawings and particularly to FIG. 1 thereof wherein a perspective view of the overall novel wood chipping apparatus is depicted. At the heart of the apparatus is a rotatable disc means generally designated which, in the preferred inventive embodiment, comprises a generally planar circular plate constructed of heavy steel or the like. The circular plate has a planar face surface 12 as well as a planar rear surface 14 (FIG. 4) and is joumalled for rotation beneath an arcuate cover plate 16 of the machine housing 18. Disc 10 is rotatably driven in the direction of arrow 20 by means of a non-illustrated motor acting through a belt and pulley arrangement 22 disposed on shaft 24. In a manner which will be discussed in far more detail hereinbelow, a plurality of knives 28 are disposed in throughbores 30 of the rotating disc or plate 10, and project outwardly from the planar face surface 12 thereof a predetermined distance.

A feed chute designated 31 is disposed on housing 18 and defines a feed means for delivering wood stock toward the rotating disc [0. Feed chute 31 is preferably disposed at an angle to the planar face surface 12 of the disc 10, such that wood deposited in the feed chute is advanced by gravity toward the disc means 10 transverse to the plane of rotation thereof whereby an interaction with the projecting knives takes place. Alternatively, if desired, a power feed advance for the wood stock, such as a conveyor mechanism or the like, could be utilized in lieu of or in conjunction with the angled feed chute. An adjustable anvil plate 33 as shown in FIG. 2 may be associated with the chute to set anvil-to-disc clearance.

The over-all apparatus of the instant invention is also seen to include a hopper assembly 32 disposed in housing 18 beneath the rotating disc or plate 10 and generally adjacent the rear planar surface 14 thereof. Hopper 32 serves to collect wood chips which are produced by the rotating disc 10, these wood chips passing through the disc from the face surface 12 to the rear surface 14 thereof via a portion of the throughbores 30 therein defining knife slots as will be more fully explained.

With the general structural configuration of the machine now firmly in mind, reference is made to the detailed construction of the rotatable disc or plate 10 which is most clearly seen in FIG. 4 of the drawings wherein a plan view of the rear planar surface 14 thereof is illustrated. The plurality of throughbores 30 in disc 10 are preferably of square construction and are disposed in disc 10 at different radial distances from the rotational axis 35 thereof. In the preferred embodiment, the plurality of throughbores 30 are disposed about the rotating plate or disc 10 in a spiral curve and are oriented such that the edge surface 37 thereof closest to the outer perimeter of disc 10 is inclined at an angle, preferably about 36, to its associated radius 34.

A knife assembly such as depicted in FIG. 5 is inserted through each of the throughbores 30 of the disc 10 in the fashion illustrated in FIG. 2 such that the cutting edges 36 and 38 of the knives 28 project outwardly from the planar face surface 12 of the disc. A plurality of such knife assemblies when disposed in the disc 10 will be seen to broadly define a cutting means which cuts the surface of the wood stock to be converted into chips simultaneously in multiple directions and at a predetermined depth. Each knife assembly of FIG. 5, of course, includes a cutting knife 28 which defines a first, generally elongated cutting edge 36 and a second adjoining cutting edge 38, preferably disposed orthogonally or at an angle of with respect to the first cutting edge 36. When compared with the length of cutting edge 36, the length of cutting edge 38 will be seen to be relatively short. The tapered wedge surfaces 40 and 44 leading to cutting edges 36 and 38, respectively, preferably define an angle of draw or intersection with associated planar elongated shanks 42 and 46 of knife 28 within the range of 28 to 40, although an angle of 36 has been found to be most suitable. The knives 28 thus comprise so-called wing knives with an L-shaped configuration.

Associated with each knife is a holding means preferably comprising holding plates 48 and 50, respectively, whereby the knives can be secured at difierent positions therein and to the disc 10. Holding plate 48 includes an inclined ramp-like projection 52 near the central region thereof as well as a groove 54 disposed adjacent one side surface of the ramp. Throughbores 56 adapted to receive bolts 58 are provided through table surfaces 60 disposed to either side of the inclined ramp 52 and which terminate in extending fingers 62. The knife 28 is adapted to be placed over the inclined ramp 52 such that the elongated shank 46 of the knife is disposed within groove 54 and such that the underside of the knife itself abuts with the top surface of the inclined ramp.

The other holding plate 50 generally defines a rectangular block having a hollowed-out central region 64 which is inclined upwardly and towards the rear of the block as view in FIG. 5 at the same angle as ramp 52. Two opposite diagonal portions 68 and 70 of end surface 66 of plate 50 are preferably beveled whereas at least the other diagonal portion 72 is chamfered, the beveling and chamfering providing clearance during the wood shipping operation. Plate 50 is adapted to be securely coupled with plate 48 in mating relation thereto and in a fashion such that plate 50 and plate 48 together form a clamp for the knife 28. Reference is made to FIG. 2 for a clear illustration of the assembled structure.

As mentioned above, the knife assembly of FIG. 5 is adapted to be inserted into the throughbores 30 of the rotatable disc or plate 10 from the rear planar surface 14 thereof. Once inserted, holding plate 50 is fixedly secured to the disc 10, preferably by welding or the like, and the projection of the knives 28 from the planar face surface 12 of disc 10 is adjusted by momentarily loosening bolts 58 maintaining the two holding plates together. As illustrated in FIG. 2, each knife 28 of the plurality of knives is adjusted such that it projects substantially the same distance from the face of the disc 10. The orientation of the knives and the holding means therefor in the disc 10 is such that the first cutting edge of each knife 28 generally extends parallel to the planar surface 12 of the disc in a single common parallel plane whereas the adjoining second cutting edge 38 of each knife extends generally transverse to and towards the planar face surface 12. The underside of each knife 28 and the adjoining bottom surface 72 of each holding piece 48 partially delimit the walls of knife slots 74 formed within throughbores 30 of disc 10. As illustrated, the shank portions of knives 28 are oriented in disc at an angle such as between 28 and 40 with respect to the planar face surface 12 thereof, such angle preferably being 36.

The specific preferred orientation of the inserted knife assemblies when viewed from the planar face surface 12 of the disc 10 can best be seen in FIG. 3 wherein it will be noted that, by virtue of the inclined disposition of the throughbores 30 with respect to the various associated plate radii 34, the cutting edges 36 of the knives are not radially aligned but are inclined at the same angle with respect to their associated radii. Further, the dispostion of the knives along the spiral curve is such that the differences in radial distances between adjacent knives in the spiral curve, such difference being illustrated by reference numeral 80, is less than the length of the first cutting edge 36. In this fashion, the first cutting edges 36 of the various knives sweep through overlapping cutting paths during rotation of the disc 10. In effect, then, the provision of a plurality of knives along a spiral curve in the manner illustrated creates an oscillatory stepwise movement of the cutting knives in a lateral or generally radial direction. Wear plate segments 71 are contemplated to smoothly connect the individual assemblies and to protect the disc surface as well.

The operation of the novel apparatus can best be described by reference once again to FIG. 2 of the drawings. Wood stock 82 of virtually any length and being taken from bulk waste, as described, is inserted into the feed chute 31 of the machine without regard to fiber orientation. As the wood stock 82 drops by gravity down the feed chute 31, the leading surface 84 of the wood stock would make contact with the rotating knives 28 on disc 10. Specifically, contact would be made with one of the knives 28 that is disposed relatively radially inwardly along the spiral curve with respect to other knives 28 which have a cutting path crossing the surface 84 of the stock. This is the case as the orientation of the spiral curve and direction of rotation of the disc 10 cause the knives to cut from the inside of the disc toward the outer perimeter thereof. In FIG. 2, the first contacting knife is illustrated as the lower knife 28.

Now, a segment of wood would be cut by the first contacting knife from the surface 84 of the wood stock 82 as the knife,

circumscribed its arcuate cutting path, with cutting edges 36 and 38 simultaneously cutting the wood in multiple directions. This segment would have a predetermined depth fixed by the distance of protrusion of knife 28 from the face surface 12 of the disc 10 or, more accurately, from the surface 66 of holding plate or member 50. The width of the segment cut would in essence be determined by the projected length of the first cutting edge 36 along the disc radius. The length of the segment cut would, of course, depend upon the dimensions of the surface 84 of the wood stock as the knife 28 would circumscribe an arcuate cutting path completely therethrough. The segment of wood so cut is designated by reference numeral 86 and such segment essentially travels up the underside of the knife 28 until contact is made with the lower surface 72 of the associated holding plate 48, this contact breaking the segment 86 into a plurality of uniform wood chips 88, which chips travel through the knife slots 74 of disc 10 and drop, by gravity, into the hopper 32 of housing 18. Since the wood segment 86 is taken from the surface 84 of wood stock 82 by means of the simultaneous cutting action of cutting edges 36 and 38, which edges are preferably disposed in orthogonal directions, cross-grain cutting of the wood stock 82 is always ensured and thus, splintering cannot take place.

As the disc 10 further rotates, the next adjacent knife along the spiral curve disposed at a slightly greater radial distance from the center of rotation of the disc comes into contact with the wood stock surface 84. This second contacting knife is exemplified by the knife disposed at the top of the drawing in FIG. 2. Now, in a fashion similar to that already described with respect to the first contacting knife, this next contacting knife will remove a segment of wood 90 from the surface 84 as the knife circumscribes its arcuate cutting path, this segment 90 being of a breadth or width equal to the difference in radial distances between adjacent knives, having a depth equal to the depth of projection of the cutting edge 36 from the planar face surface 12 of the disc 10, and having a length as determined by the dimensions of the wood stock surface itself. Segment is broken into a plurality of uniform chips 92 in a similar fashion, these chips likewise being deposited into the hopper 32.

In a stepwise, sequential manner due to the spiral disposition of the knives, additional adjacent segments of wood will,

be sliced from the surface 84 of the wood stock until such surface has been totally cut away thus essentially exposing a new, underlying planar surface 94. Surface 94 would then be cut in a similar manner by the individual knives and the process would proceed until the entire piece of stock 82 has been consumed and converted into chips having uniform dimensional characteristics. Of course, it will be recognized by those skilled in the art that the foregoing description of operation has been simplified so as to facilitate understanding, and that a plurality of knives in the spiral will usually simultaneously act upon the wood stock. It should further be appreciated that more than one spiral curve can be provided, if desired.

In actual practice, a machine constructed in accordance with the novel concepts described herein has been found to produce wood chips of such uniformity as to constitute a signal advance in the art. Specifically, using stock comprising sawmill waste 2 X 6 by 3-10 inches long, approximately 96.7 percent of the chips out had dimensions from one-fourth inch through three-fourths inch. With waste 2 X 6 by 18-36 inches long, 98.2 percent of the chips cut had dimensions from onefourth inch through three-fourths inch. The novel inventive apparatus is also capable of utilizing roundwood, if so desired, with equally consistent results. With roundwood of 4 to 5 inches diameter, fully 98.1 percent of the chips so produced were found to have dimensions from one-fourth through three-fourths inch. Short length or lily pads can also be favorably utilized.

As should now be apparent, the objects initially set forth at the outset to the specification have been successfully achieved.

Accordingly, I claim:

1. A wood chipper comprising: disc means, means for rotating said disc means, feed means for delivering wood stock towards said disc means transverse to the plane of rotation thereof; cutting means disposed on said disc means for simultaneously cutting the surface of said wood stock in multiple directions and at a predetermined depth, said disc means comprises a generally planar circular plate, and (wherein) said cutting means comprise a plurality of knives protruding from a planar surface of said plate, each knife having a first cutting edge generally extending parallel to said planar plate surface and an adjoining second cutting edge generally extending transverse to and towards said planar plate surface; and said knives being disposed about said plate surface at different radial distances from the rotational axis thereof.

2. A wood chipper as defined in claim 1, wherein said knives are disposed about said plate surface in a spiral curve.

3. A wood chipper as defined in claim 2, wherein each knife protrudes from said planar surface of said plate the same distance, whereby said first cutting edges of said knives are all disposed in a single plane parallel to said plate surface, said distance of protrusion determining the depth of cut.

4. A wood chipper as defined in claim 3, wherein each knife in said spiral curve is disposed at a different radial distance from the rotational axis of said plate.

5. A wood chipper as defined in claim 4, wherein the difference in radial distances of disposition between adjacent knives in said spiral curve is such that said first cutting edge of said knives sweeps through overlapping cutting paths during rotation of said plate 6. A wood chipper as defined in claim 5, wherein said first cutting edge of each knife is disposed at an angle to an associated plate radius.

7. A wood chipper as defined in claim 6, wherein each knife comprises an L-shaped wing knife, and wherein throughbores are provided through said plate along said spiral curve, hold- 

1. A wood chipper comprising: disc means, means for rotating said disc means, feed means for delivering wood stock towards said disc means transverse to the plane of rotation thereof; cutting means disposed on said disc means for simultaneously cutting the surface of said wood stock in multiple directions and at a predetermined depth, said disc means comprises a generally planar circular plate, and (wherein) said cutting means comprise a plurality of knives protruding from a planar surface of said plate, each knife having a first cutting edge generally extending parallel to said planar plate surface and an adjoining second cutting edge generally extending transverse to and towards said planar plate surface; and said knives being disposed about said plate surface at different radial distances from the rotational axis thereof.
 2. A wood chipper as defined in claim 1, wherein said knives are disposed about said plate surface in a spiral curve.
 3. A wood chipper as defined in claim 2, wherein each knife protrudes from said planar surface of said plate the same distance, whereby said first cutting edges of said knives are all disposed in a single plane parallel to said plate surface, said distance of protrusion determining the depth of cut.
 4. A wood chipper as defined in claim 3, wherein each knife in said spiral curve is disposed at a different radial distance from the rotational axis of said plate.
 5. A wood chipper as defined in claim 4, wherein the difference in radial distances of disposition between adjacent knives in said spiral curve is such that said first cutting edge of said knives sweeps through overlapping cutting paths during rotation of said plate.
 6. A wood chipper as defined in claim 5, wherein said first cutting edge of each knife is disposed at an angle to an associated plate radius.
 7. A wood chipper as defined in claim 6, wherein each knife comprises an L-shaped wing knife, and wherein throughbores are provided through said plate along said spiral curve, holding means disposed in said throughbores for securing each knife in said plate at an adjustable distance of protrusion and at an angle from said planar surface thereof, a portion of each holding means defining a knife slot in communication with its associated plate throughbore, whereby chips of wood cut by each wing knife are carried through said slot and associated throughbore to the other side of said plate. 